What does "amplitude" measure in music?

Amplitude in music refers to the measurement of the strength or intensity of a sound wave, which directly correlates to how loud or soft the sound is perceived. When sound waves have greater amplitude, they produce louder sounds; conversely, sounds with lower amplitude are perceived as quieter. This concept is crucial in music, as dynamics—ranging from soft to loud—contribute significantly to the overall expression and emotional impact of a piece.

The other options focus on different aspects of musical elements. Pitch frequency relates to the perceived highness or lowness of a note, tempo speed pertains to the pace at which music is played, and musical texture refers to the complexity of a musical composition through the layering of different instruments or voices.